There are two ways to
cut the same stone (actually there are a lot more than
that), and each takes a different approach. A new faceter
probably needs to know this as there are two types of
Faceting Diagrams and they work a little differently. The
older method uses diagrams like those in the Vargas book,
and involve cutting the stone starting with the MAINs and
then adding all the other facets. This means that you are
often trying to match two points on the stone as you
cut.

The newer method
(called Meet Point) sets up instructions so that all facets
are cut to one and only one point at a time. The idea is cut
each successive round of facets so that there is only one
point on the stone with which each must
align.

There are pros and
cons for each method. The positive aspect of the old method,
is that there is less loss during the cutting process.
Another way to look at it is that for the same size piece of
rough, the older method, can produce a larger
stone.

Meet Point faceting
means more loss, but faster and easier cutting. You spend
for less time nudging a newly forming facet to meet two
points at the same time, and more time just watch one place
move to another. I was taught on the first method, but have
migrated to the second.

I still use the Vargas
books, but have to translate the cutting diagrams to the
meet point procedure. It is done like this.

Here are the typical
Instructions for cutting as given in the Vargas books, This
is for cutting a standard 57 facet round brilliant stone
using a 32 index gear.

Eight main
facets
(M)
at culet angle, on eight fold asterisk settings.
Bring the top of facet just to
girdle.

C3.)

Eight star
facets
(S)
at crown angle less 15°, on settings at
midpoint of those in step 3. Cut till tip just
matches the break tip.

C4.)

Cut the table
(T)
at
0°,
to meet C2 and C3 facets

Fundamentally you
reverse the order of cuts on the pavilion facets. You cut
breaks to a single point at the culet, then define the
girdle, an finally cut the mains from the cult stopping at
the girdle. The depth of the breaks is fixed by the the two
cutting angles. If you wish a little more depth for the
breaks, then subtract
1/2-1°
from the mains.

The crown too is
mostly reversed in cutting order. The meet point method
provides a little less choice in placing the height of the
break facets as their meet point is defined automatically
when the mains are cut. Adjusting the mains culet angles
will change the break facet height. (Its just a different
way of thinking about their placement and
position.)

By the way, there is
more loss using this method is because the pavilion breaks
are cut first. They must be brought to a point, and are at a
higher angle than the mains. Because of he higher angle, the
gem will be narrower than one created by cutting the mains
first.

By cutting the breaks
first the rough must be a bit longer as shown in the
diagram. If the mains are cut first, then the final culet is
establish immediately, and there is no further loss at the
culet end. The two red areas represent the additional loses
necessary with the meet point method, while maintaining all
other proportions the same. It is not a lot but it does add
up. I still prefer this method for the ease of cutting it
introduces, and gladly give up the extra rough. (Not shown
is a small additional loss at the girdle when using the
Mains First method. It is negligible compared to the loss
with the Meet Point method.)